SK hynix ADR tumbles 9%, dragging Samsung Electronics down 9%, SK hynix 11% in Seoul

Samsung Electronics and SK hynix extended their losses during morning trading Thursday, tumbling roughly 9% and 12%, respectively.

As of 10:30 a.m. Thursday, Samsung Electronics was trading around 250,000 won ($168), down about 9% from the previous session. SK hynix had fallen 248,000 won, or 11.91%, to 1.83 million won.

Samsung Electronics opened down about 5% at 264,500 won before sliding to an intraday low of 252,500 won, a decline of roughly 10%. SK hynix opened down about 9% at 1.9 million won and fell further to 1.82 million won, a drop of approximately 13%.

Both stocks had surged 6.27% and 8.83%, respectively, on Wednesday, but sentiment reversed sharply after renewed concerns over a slowdown in AI infrastructure investment emerged overnight on Wall Street.

In New York overnight, Micron tumbled 8% and Intel fell 4.7%. AMD and Lam Research each dropped around 3%, pushing the Philadelphia Semiconductor Index down 2.1%. SK hynix's American depositary receipts fell $17.46, or 9 percent, to close at $176.46.

Morgan Stanley said in a recent report that cancellations and delays of data center projects are increasing due to rising electricity costs and environmental burdens, lending more concrete form to longstanding concerns about a slowdown in AI infrastructure investment.

The simultaneous plunge in Samsung Electronics and SK hynix — the two largest stocks by market capitalization on the Kospi — amplified the broader index's losses. At the same time, the Kospi was down 508.46 points, or 6.98 percent, at 6,775.95. The index had opened down 323.91 points, or 4.45 percent, at 6,960.50 before extending its losses during the session.

A sell-side sidecar — a temporary halt on sell program orders — was triggered on the Kospi market early in the session. It was the first sell sidecar in three trading days since Monday, coming just one day after a buy sidecar was activated on Wednesday.